Pen



FIG. 1 is a front perspective view of a pen showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front elevational thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view.

The broken lines in FIGS. 1 to 8 are for environmental purposes only and form no part of the claimed design. The stippling shown on the pen represents shading and is not part of the claimed design. 

The ornamental design for a pen, as shown and described. 